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Measure the Tip Radius

Tip radius may be measured using a tip characterizer sample and the Tip Qualification function in NanoScope or NanoScope Analysis software (NanoScope software does not include the Estimated End Radius function). Refer to the NanoScope Software User Guide for details.

  1. Scan (Peak Force QNM in Air mode) the characterizer sample. Set the Scan Size to approximately 1.5mm. Characterizer image size is important because, along with Tip Image Size and feature density, it determines how many peaks are used for the tip estimation.
 
  1. Set the Samples/Line and Lines to 512.
  2. Set the Aspect Ratio to 2.0
  3. Set the Scan Rate to 0.5 Hz or less.
  4. Because this is an intentionally rough sample that can damage the probe tip, set ScanAsyst Noise Threshold to 1.0 nm.
  1. Capture the characterizer image.
  1. Open the Height channel of the saved image in the NanoScope Analysis package.
  1. Flatten the image by clicking the Plane Fit icon.
 
  1. Select XY as the Plane Fit Mode.
  2. Select 1st as the Plane Fit Order.
  3. Click Execute to plane fit the image:

  1. Click the Tip Qualification icon in the NanoScope Analysis toolbar to open the Tip Qualification window.
 
  1. Enter the measured average Deformation into the Height 1 from Apex field.
NOTE: The Height from Apex parameter should equal the average penetration depth or the indentation in the force curve. The indentation can be measured as the separation from the minimum force to the peak force in the loading curve. For most samples, the indentation is very close to the sample deformation. Therefore, the average deformation can be used as Height from Apex parameter to estimate tip radius. But for very soft samples (<20MPa), the adhesion is very large and the difference between indentation and deformation is large so that the indentation must be measured from the force curves in the Force Monitor window shown in Figure 1.

Figure 1: Typical force curve of a PDMS-Soft-1 sample. Nominal modulus: 2.5 MPa.

 
  1. Click Estimate tip.
  2. Click Qualify tip. Figure 2 displays the Estimated Tip End Radius.

Figure 2: Tip Qualification Results

 

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